title: Conserved pyridoxal protein that regulates Ile and Val metabolism.
abstract: Escherichia coli YggS is a member of the highly conserved uncharacterized protein family that binds pyridoxal 5'-phosphate (PLP). To assist with the functional assignment of the YggS family, in vivo and in vitro analyses were performed using a yggS-deficient E. coli strain (ΔyggS) and a purified form of YggS, respectively. In the stationary phase, the ΔyggS strain exhibited a completely different intracellular pool of amino acids and produced a significant amount of l-Val in the culture medium. The log-phase ΔyggS strain accumulated 2-ketobutyrate, its aminated compound 2-aminobutyrate, and, to a lesser extent, l-Val. It also exhibited a 1.3- to 2.6-fold increase in the levels of Ile and Val metabolic enzymes. The fact that similar phenotypes were induced in wild-type E. coli by the exogenous addition of 2-ketobutyrate and 2-aminobutyrate indicates that the 2 compounds contribute to the ΔyggS phenotypes. We showed that the initial cause of the keto acid imbalance was the reduced availability of coenzyme A (CoA); supplementation with pantothenate, which is a CoA precursor, fully reversed phenotypes conferred by the yggS mutation. The plasmid-borne expression of YggS and orthologs from Bacillus subtilis, Saccharomyces cerevisiae, and humans fully rescued the ΔyggS phenotypes. Expression of a mutant YggS lacking PLP-binding ability, however, did not reverse the ΔyggS phenotypes. These results demonstrate for the first time that YggS controls Ile and Val metabolism by modulating 2-ketobutyrate and CoA availability. Its function depends on PLP, and it is highly conserved in a wide range species, from bacteria to humans.
authors.affiliation: Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi, Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Ito
authors.forename: Jumpei
authors.initials: J
authors.lastname: Iimori
authors.forename: Sayuri
authors.initials: S
authors.lastname: Takayama
authors.forename: Akihito
authors.initials: A
authors.lastname: Moriyama
authors.forename: Ayako
authors.initials: A
authors.lastname: Yamauchi
authors.forename: Hisashi
authors.initials: H
authors.lastname: Hemmi
authors.forename: Tohru
authors.initials: T
authors.lastname: Yoshimura
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics; D002087:Butyrates / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D003065:Coenzyme A / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D007532:Isoleucine / Q000378:metabolism*; D011485:Protein Binding; D011732:Pyridoxal Phosphate / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D014633:Valine / Q000378:metabolism*
chemical_list: D002087:Butyrates; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C585834:YggS protein, E coli; D007532:Isoleucine; D011732:Pyridoxal Phosphate; C005087:alpha-ketobutyric acid; D014633:Valine; D003065:Coenzyme A